´88 115HP il6 rebore -update

[savasa]

Hi!<br />I am in a middle of a powerhead rebuilt, due to a bad water cover jacket. Two of the jugs need to be rebored. I have heard from Merc pros. that the cyls have to be bored to the spec in the merc service manual instead of bringing along the oversized piston to the workshop.<br /><br />The reason is that the bore operator is not aware of that mercs need more clearence between piston rings and the cylinder walls compared to regular car engine. And therefore it is a greater chance for the piston get stucked when the engine is running.<br /> <br />And would the engine be better of with a new water cover jacket from the merc dealer then looking for a second hand. (Yes in my country<br />about 95 % of all outboards runs in saltwater)<br /><br />Thanks for every answers! <br /><br />-G-

 

[achris]

Re: ´88 115HP il6 rebore -update

the cyls have to be bored to the spec in the merc service manual instead of bringing along the oversized piston to the workshop.

Absolutely correct! for all the reasons you stated.<br /><br />Better with a new cover? If you are going to the expense of a full rebuild and a couple of new pistons, why would you risk all that on a secondhand cover? Also use the correct adhesive on the cover bolts (Resi-weld), and the correct torque. Don't be tempted to overtighten them. Overtightening distorts the cover and volia, water leaks again.<br /><br />Chris............

 

[Dhadley]

Re: ´88 115HP il6 rebore -update

We see this all the time from automotive shops that are not accostumed to boring outboards. If possible get the block to a marine machine shop. You'll save yourself a ton of heartaches.

 

[savasa]

Re: ´88 115HP il6 rebore -update

Yes Dhadley good to hear.<br /><br />I remeber an episode I had some years ago rebuilding a 70 hp 3 cyl. When I delivered the block to the repairman at my localworkshop (a guy that at least been working there for more than 40 years). The old man in the workshop couldn´t almost understand what I was trying to say to him that he should only bore the jug to a number on a peace of paper instead of having the new oversized piston in his hands. His face looked like a big question mark. But anyway in the end it went well.<br /><br />It is very good to have so extremly experienced people to ask here on this forum <br /><br />Thanks!<br />-G-

 

[Clams Canino]

Re: ´88 115HP il6 rebore -update

I'm running into that problem since I moved. Veteran machine types - very good. Just can't get that I want 2.890 ALL the time - every time.<br /><br />-W

 

[savasa]

Re: ´88 115HP il6 rebore -update

Hi everybody!<br />I´ll give you little update. <br />A couples of days ago I went to the workshop with the cyl block. As I said earlier I believed that 2 of the jugs needed some attension. After a good cleaning it looked like I maybe could get off with only some honing. No big scratches inside the cylinders only some rust on the surface. <br /><br />And now the fun part. The guy in the workshop measured all 6 jugs and guess what..... 3 of ´em are worn ,002" and the rest were ,0035" funny.... <br /><br />After some wild and loud screaming (alone in my garage of course)I have to decided to spoil my beast with 6 new ,020" wisecos. I know for you in the Us this is maybe a little over the top, but where I live inline 6´es don´t grow on trees.(or have never as log as inline 6 were produced) Getting parts can sometimes be a bit tricky when most of them runs in saltwater. I´ll keep you posted, if you want.<br /><br />-G-

 

[jheron]

Re: ´88 115HP il6 rebore -update

Hey Gava you can get persian pistons which are better than the forged wisecos for this application. Send Clams Canino an email and he can set ya up

 

[Clams Canino]

Re: ´88 115HP il6 rebore -update

Wiseco are not advised for the direct charge inlines due to the different expansion properties of the forged pistons. Use Mercury or Persan. I'm testing Vertex in my own motor as we speak.<br /><br />Further, that wear could be fixed with .010 over, why thin out the walls? <br /><br />-W

 

[Dhadley]

Re: ´88 115HP il6 rebore -update

The Wisecos will be fine. Make sure you use the 31 series (coated) not the 30 series (uncoated). There are differences.<br /><br />Clams -- the Vertex are excellent cast pistons but just in case no one mentioned it, the coating will wear off so dont be surprised. Its a break-in coating only. Not like the Electra coating.

 

[Clams Canino]

Re: ´88 115HP il6 rebore -update

I dissagree wholeheartedly about the Wisco... The inlines were designed with *cast* pistons and the expansion properties of the forged Wiseco are not what the Cods intended for thee direct charge inlines. (please note: I make more profit selling Wisco than Persan - I just talk them out of Wiseco anyway)<br /><br />Why not Wisco? They expand differently.<br />I'm doing a 115 that overheated #1 and to some degree #2. Usually the cast pistons overexpand on the ports axis and score and melt a bit.<br /><br />These Wisco pistons instead did it on the wrist pin axis. Letting the wrist pins come loose inside the pistons. This wipred out both rods and the #1 crank journal. I'm sure this would not have been the case with a cast piston.<br /><br />Roger on the Vertex...... that's good to know. And they come in a neat little sock too. <br /><br />As far as the break-in coating wearing off... you think I was gonna go in and look (unless a problem arised)?<br /><br />My current job in progress invloves the failure of #1 on a 6 piston Wisco replacement. I'm still perplexed as to the cause of the failure. But it took the crank with it.<br /><br />-W

 

[savasa]

Re: ´88 115HP il6 rebore -update

Hi guys!<br />It´s nice to get some good piece of advise for my overhaul.I´ve not ordered pistons and blockboring yet. So I´am open for all inputs. The MOST important for me is to have a good tower that runs well in many years ahead (with a good maintenance). I don´t want to have a breakdown in the near future, due to a wrong desission now.<br />Thanks!<br /><br />-G-